This study explores the role of teacher leaders in school development, focusing on their dual responsibilities in teaching practice and broader organizational improvement. It investigates how Swedish teacher leaders balance their teaching duties with school development tasks, contributing to both areas. The research questions address teacher leaders' approaches to teaching and school development, their experiences of leading colleagues, and their progression in leadership capacity. The study involves interviews with over 20 teacher leaders from six compulsory schools, analyzing their engagement in teaching and broader school development. The 20 teacher leaders interviewed constitute a group of informants with experience in a wide range of challenges, student populations, and teaching staff. The analysis was conducted in several stages, beginning with an initial qualitative review of participants' experiences, followed by more theory-driven analyses grounded in previous research on teacher leadership and informed by Fairman and Mackenzie's model of capacity building. Findings reveal that teacher leaders emphasize systematic reflection on teaching and collaborative efforts for school improvement. However, challenges include engaging colleagues in broader development initiatives and navigating the transition between teaching and organizational leadership. The study concludes that while teacher leaders play a crucial role in school development, further research is needed to understand how to support their dual responsibilities effectively.